Incandescent electric lamp



(No Model.) J. W' -SWAN' INGANDESGB'NT ELECTRIC LAMP. No.,260,335. Patented June 27, 1882..

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UNITED STATES PATENT OFFICE.

JosnPH w.'swA, oF NEwcAsrLn-UPoN-TYNE, ENGLAND.

INCAN DESCENT ELECTRIC LAlVI P.'

SPECIFICATION forming' part of Letters Patent No. 260,335, dated June 27, 1882. Application filcd April 17, 1882. (No model.) Patentcd in England September 29, 1881, No. 4,202.

w Ireland, and residing at the town of Newcastleupon-Tym, England, chemist, haveinvented certain Improvements in and relating to Incandescent Electric Lamps, (for which I have obtained a patent in Great Britain, No. 4,202,

dated September 29, 1881,) of which the following is a specification.

My invention relates to an improvement in electric lamps wherein light is produced by heating to a high degree of incandescence a thin filament of carbon contained in a vessel from which atmospheric air has been exhausted, or which contains gas which does not destroy the incandescent carbon filament.

The particular object of my invention is the rendering more perfect than hitherto the contact or connection between the ends of the carbon filaments and the metallic sockets and wires which convey the electric current to and from the filaments.

Hitllerto it has been found almost impossible to make a sufficiently perfect contact between the filaments and the metallic sockets by the compression of the sockets on the filaments,the tendency being in that case to local action of the electric current at the points of contact, and consequent excessive heating of those parts and disintegration of the carbon, with the final result of the lamp-glass becoming obscured and the sockets fusing. To avoid this great difficulty and defect in the construction of the lamps referred to, I, so to say, weld or cement together by' means of a deposit of hard carbon the ends ofv thefilament and the metallic sockets into which the ends are inserted. My mode of procedure in accomplishing this' object is as follows: v

I make the metallic sockets which receive the ends of the carbon filament of any suita- I ble metal, but preferably of platinum, and of a form varied to correspond with the shape of the filament. If it be a filament of a cylindrical section, I form the ends of the two wires to which the filament is to be attached into a tube of the size and shape of the end of the filament. lf the filament be flattened so that its section is a line of greater or less length,

then I shape the sockets so that the ends of thefiat-tened filament are held between sockets which are flat surl'aees of metal. The sockets having been formed as described, I attach them to a short stem of glass rod or tubing by fusion by means ot' a blow-pipe. so as to be connected together firmiy in pairs, and with the sockets in the proper position relatively to each other to receive the ends of the carbon filament, which is nsually'of the form of aloop or arch, sometimes with one or more spiral convolutions. Into the sockets t-hus arranged I insert the ends of the carbon arch, the sockets and filaments being -relativcly of the proper form, so as to fit closely to each other. I then treat the mounted filaments in one or other of the following waysthat is, to say, I coat the filament with copper by any wellknown electrotypc process in every part except the parts inserted in the socket and a very short length beyond, amounting to about one milliineter, or even less. After removal from the electrotyping-bath I carefully Wash and dry the filament, and I then immerse itin a bath of aniline-oil, chloroform, benzole, benzoline,oliVe-oil, or any other suitable liquid or vapor from which carbon deposits by the action of heat, and while immersed in one or other of these liquids I pass an electric current through the filaments, the electric current being of such strength that the parts of the filaments on which there is no deposit of copper, and also the ends of the sockets and some distance from the ends of the sockets, become so strongly heated that a deposit of carbon takes place at and upon those parts; and I Continue the operation until a considerable deposit of carbon, resulting in a bulbous enlargement of the parts on which it has taken place, is produced, and the welding together of the sockets and ends of the Vfilaments already referred to is efi'ected. The copper deposit is removed in any suitable way.

Instead of loealizing the heating of the parts on'which the carbonaceous deposit is required to take place, in the mannerdescribed, the same end may be obtained or el'ected as i'ollows: I immerse the filaments in a bath of mercury or other suitable liquid metal nearly u'p to the point of attachment' to the sockets, a suitable ICQ carbonaceous liquid or vapor filling the bath above the mercury or other suitable liquid metal, and an electrical current of suitable strength, as before dcscribed, beingthen passed through the connecting-wires and the portion of thefilament notimmersed, the carbonaceous deposit before described will be produced; or a similar result may be obtained by placing a bridge, of metal or carbon, in the nature of a clip formed by two bars of metal or carbon held together by two slight springs, across the carbon filaments mounted, as already described, at a point very near to the point of attachment to the sockets, and so as to divert the current of electricity from passin g entirely' through the entire length of the filament, so as to contine such current to that portion of the filament adjacent to the socket, and which is required to be locally heated.

The mounted filament, with thebridging clip across it,is then immersed in the carbonaccous liquids or vapors already referred to, and electricity is passed through the connecting-wires, as before described, and so as to produce the desired local heating and the required deposit of carbon.

In the accompanying d1'awings,Figure l represents the finished article, A being the carbon filament; B, the sockets; O, the glass between the sockets, and D the carbon deposit; and Fig. 2 is a diagram illustrating the welding or nniting operation. In said latter figure the carbon filamen t, the socket, and the glass are let-tered as in Fig. 1, while E is a vessel containing aniline-oil, in which the filament and ends of the socket are immersed; F, the copper deposit, and G the wires for conveying the electric current to the sockets.

Aniline-oil is preferably used as the medium from which carbon is deposited, as I have from 40 my experiments found it to possess special advantages in this regard.

Having now fully described my said invention and the manner of carrying the same into eifect, what I claini is- 1. In an incandescent electric lamp, a carbon filament united by a carbon deposit of the character described to the metallic sockets, substantially as set forth.

2. The method of uniting the ends of the 5o carbon filaments to the metallic sockets by prodncing a local electrical heating, and thereby forming a coating or deposit over the junction, substantially as described.

3. In the production of a carbon deposit through electrical heating, the improvement consisting in immersing the article to be c0v ered in aniline-oil and clectrically heating it while so immersed,snbstantially as described.

4. In producing the local carbon deposit above mentioned, the improvement consisting in applying a metallic deposit by electrical action to the part of the filament required to be kept cool, and on which. the carbon deposit is not to take place.

In witness whereof I have signed my name to this specification in the presence of two subscribing witnesses.

, JOSE PH SV. SVVAN.

Witnesses:

Rom'. GREENE WALDEN, Solic'itor, Nwcastlc-upon-Tync.

FRnDEarcK WALTER DENDY, Solictor, Ncwcastle-upon-Tyne, England. 

